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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

The effect of Carbopol 934 rheological polymers on the dissolution rate of sulphamide crystals

Muungo, Lungwani Tyson Makoye January 1995 (has links)
No description available.
2

Enzymatic treatement of wastewater sludge in presence of a cation binding agent : improved solubilisation and increased methane production

Beijer, Ronja January 2008 (has links)
Stockholm Water is a water and sewage company with Henriksdal as one of two wastewater treatment plants (WWTPs). At Henriksdal wastewater sludge generated in the wastewater treatment process is digested which generate biogas; a mixture of mainly methane and carbon dioxide. If purified to methane content of 96 - 98 % this gas is called biomethane. Biogasmax is a project aiming to reduce the use of fossile fuels in Europe by providing that biogas is a good technical, economical and environmental alternative as vehicle fuel. The specific aim for Stockholm Water is to increase the biogas production at the existing plant in Henriksdal. Enzymatic treatment of wastewater sludge is an innovative technique earlier proofed to increase the biogas production from wastewater sludge with up to 60 %. The enzyme activity is in turn proven to significantly increase in the presence of a cation binding agent. One aim with this thesis was to investigate if the sludge from Henriksdal wastewater treatment process at all is affected of enzymatic treatment in presence of a cation binding agent since this has shown to have some significance. The chemical oxygen demand (COD) was measured in the liquid phase of sludge after treatment and used as a measurement of treatment effect. Another aim of this thesis was to look into the possibility to increase the methane production from sludge at Henriksdal WWTP. This was investigated through batch laboratory digestion tests. The sludge from Henriksdal WWTP was shown to be a good substrate for the enzymes added. COD in the liquid phase was increased with 17 – 32 % depending on the dose of enzymes and sodium citrate added. Digestion of sludge with a total addition of 18.6 mg enzymes per 1 g total solids (TS) and a concentration of 5 mM sodium citrate increased the methane production with almost 18 % compared to untreated sludge. This equals an increase of 18.3 % when converted to represent a totally blended and continuous digestion chamber at Henriksdal WWTP. The increased methane production also results in a sludge reduction out from the digestion chambers. The increased methane production and sludge reduction though does not fulfil the increased costs for the enzymes and sodium citrate applied. These doses must be decreased and the costs for both enzymes and sodium citrate must be reduced for this technique to be economically feasible in a full scale operation.
3

Enzymatic treatement of wastewater sludge in presence of a cation binding agent : improved solubilisation and increased methane production

Beijer, Ronja January 2008 (has links)
<p>Stockholm Water is a water and sewage company with Henriksdal as one of two wastewater treatment plants (WWTPs). At Henriksdal wastewater sludge generated in the wastewater treatment process is digested which generate biogas; a mixture of mainly methane and carbon dioxide. If purified to methane content of 96 - 98 % this gas is called biomethane.</p><p>Biogasmax is a project aiming to reduce the use of fossile fuels in Europe by providing that biogas is a good technical, economical and environmental alternative as vehicle fuel. The specific aim for Stockholm Water is to increase the biogas production at the existing plant in Henriksdal. Enzymatic treatment of wastewater sludge is an innovative technique earlier proofed to increase the biogas production from wastewater sludge with up to 60 %. The enzyme activity is in turn proven to significantly increase in the presence of a cation binding agent.</p><p>One aim with this thesis was to investigate if the sludge from Henriksdal wastewater treatment process at all is affected of enzymatic treatment in presence of a cation binding agent since this has shown to have some significance. The chemical oxygen demand (COD) was measured in the liquid phase of sludge after treatment and used as a measurement of treatment effect. Another aim of this thesis was to look into the possibility to increase the methane production from sludge at Henriksdal WWTP. This was investigated through batch laboratory digestion tests.</p><p>The sludge from Henriksdal WWTP was shown to be a good substrate for the enzymes added. COD in the liquid phase was increased with 17 – 32 % depending on the dose of enzymes and sodium citrate added. Digestion of sludge with a total addition of 18.6 mg enzymes per 1 g total solids (TS) and a concentration of 5 mM sodium citrate increased the methane production with almost 18 % compared to untreated sludge. This equals an increase of 18.3 % when converted to represent a totally blended and continuous digestion chamber at Henriksdal WWTP. The increased methane production also results in a sludge reduction out from the digestion chambers. The increased methane production and sludge reduction though does not fulfil the increased costs for the enzymes and sodium citrate applied. These doses must be decreased and the costs for both enzymes and sodium citrate must be reduced for this technique to be economically feasible in a full scale operation.</p>
4

Synthetic methods towards the core tricyclic ring system of pradimicin A

Zilke, Laura Carolyn Unknown Date
No description available.
5

Evaluation of Heme and Free Iron Binding Agents As Substitutes for Sodium Nitrite in Cured Meat

Vahabzadeh, Farzaneh 01 May 1982 (has links)
Nitric oxide (NO) and carbon monoxide (CO) gases, alone or with oxalate, phytate, or ethylenediaminetetraacetate (EDTA) were tested for antibotulinal activity as substitutes for sodium nitrite in ground pork inoculated with spores of Clostridium botulinum, then abused by storage at 277°C. Nitric oxide with 250 ppm oxalate or phytate was most inhibitory, while NO alone was as effective as 156 ppm sodium nitrite for inhibition of gas and botulinal toxin production in the meat system. All swollen samples contained very low levels of residual nitrite, but nitroso heme and soluble iron content did not change compared with unswollen samples of the same treatment while total heme content decreased slightly. Binding iron in the meat system did not appear to be sufficient for botulinal inhibition. Apparently, residual nitrite must be present to react directly with the botulinal cell, inhibiting growth. NO gas would not be a practical subsitute for sodium nitrite in curing, since nitrite itself is formed when meat is blended in the presence of this gas. Neither could CO be used in meat curing, since the pink color of raw, CO-treated meat disappeared after cooking. More importantly, all samples treated with CO swelled rapidly and contained botulinal toxin.
6

Synthesis and anion binding studies of pyrazole and biimidazole-containing receptors

Rubin, Bobbi Linden 01 February 2011 (has links)
This dissertation covers two different topics within the area of diaza-containing aromatic five-membered rings: biimidazoles and pyrazoles. With the exception that both these subject matters are explored in the context of developing new anion binding agents, the background and research associated with these two topics are vastly different and will be treated as such. Chapter two, dealing with biimidazoles, focuses solely on expanded porphyrins, while chapter three discusses pyrazoles as potential macrocyclic building blocks and as diamidic-functionalized anion binders. The first chapter covers several different topics in order to put into perspective the diverse subject matter presented in this dissertation. It begins with an overview of some well-known expanded porphyrins. The synthesis, classical applications, and newer studies of the biimidazole synthetic efforts are then described. The third part of the introductory chapter covers the synthesis and applications of pyrazoles. The use of heterocycles with more than one heteroatom in the construction of expanded porphyrins is just beginning to be explored, and is the focus of chapter two. The synthesis of a novel expanded porphyrin is described and its applications are investigated. More specifically, chapter two covers the synthesis of several biimidazole dialdehydes and their condensation with three 3,3',4,4'-functionalized bis-[alpha]-free bipyrroles to form a series of novel macrocycles. The characterization of these new compounds has been investigated and is discussed in detail. Also presented are preliminary studies of their anion binding properties. Pyrazoles, the subject of chapter three, are another overlooked class of potential building blocks in the area of expanded porphyrins and molecular recognition chemistry. Pyrazoles have rarely been reported in the literature as being part of a larger molecular framework. Until this work, their anion binding potential had remained unexplored. Thus, the attempted incorporation of a pyrazole fragment into an expanded porphyrin framework is described. Second, and more significantly, the design, synthesis, and anion binding properties of a new series of diamidic pyrazoles are reported. / text
7

Performance Assessment of Alternative Composite Earth Wall Panels

Gowda, Vidya 11 April 2014 (has links)
The American Society of Heating, Refrigerating and Air conditioning Engineers suggests that the building sector represents over 30 percent of our national energy consumption (Parsons, R., 2001). Embodied energy in components of building construction can represent as much as five to ten years of operating energy. Building materials such as concrete, steel and glass require significant amounts of energy for production, and therefore are important when calculating embodied energy in buildings (Keable, 2007; Rypkema, 2007). Because of the relatively large area and volume of related components, the building enclosure system represents a major factor when calculating embodied energy. Alternative materials could be incorporated by adapting traditional and vernacular building approaches to today's standards, for example, compressing soil blocks for use as external walls in buildings that can be applicable to almost any climate including rainforests and cold climates. As an alternative to high-embodied energy materials used for enclosure systems, compacted earth-based enclosure systems may be a viable option, particularly if developed and applied as a pre-manufactured modular system. This study seeks to both quantitatively and qualitatively explore the potential development of earth-based building curtain wall systems. Using modified ASTM test protocols for building enclosure systems and components, alternative earth-based panels were compared. The results suggest that earth-based panels may be a viable option for curtain wall systems but its performance is highly dependent on the composition of the panels. The results of the tests are summarized. / Master of Science

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